1. Field of the Invention
The present invention relates to a liquid crystal projector device adapted to guide light from a light source to an optical system to generate images for magnification projection on a forward screen.
2. Description of Related Art
A liquid crystal projector device has three image generating units for generating image light of three primary colors, each including an outgoing side polarizing plate, a pre-polarizing plate, a liquid crystal panel, an optical compensating plate, and an incidence side polarizing plate, which are sequentially placed (see, for example, JP 2006-39087, A). FIG. 15 shows an optical compensating plate 57 and an incidence side polarizing plate 58 held by a turning member 40 adjustable in inclination angle relative to the optical axis, and adjustable in rotation angle within a plane perpendicular to the optical axis, in order to adjust the white and black contrast of the color image light.
The turning member 40 is attached via an auxiliary member 42 to a fixing member 34. The auxiliary member 42 has a long hole 36 extending in the direction perpendicular to the optical axis. A screw 35 is screwed into the long hole 36 to attach the auxiliary member 42 to the fixing member 34. The turning member 40 has a pair of long holes 41, 41 extending in the direction parallel to the optical axis. A pair of screws 43, 43 are screwed into the pair of long holes 41, 41 to attach the turning member 40 to the auxiliary member 42.
In adjusting the rotation angle of the incidence side polarizing plate 58 held by the turning member 40, the screw 35, which has attached the auxiliary member 42 to the fixing member 34, is loosened to allow the auxiliary member 42 to slide along the long hole 36. This causes the incidence side polarizing plate 58 to rotate to make a so-called black adjustment.
In adjusting the inclination angle of the optical compensating plate 57 held by the turning member 40, one of the screws 43, which has attached the turning member 40 to the auxiliary member 42, is loosened to allow the turning member 40 to slide along the corresponding long hole 41. This varies the inclination angle of the optical compensating plate 57 to make a so-called color shading correction.
However, there has been a problem. Because the conventional liquid crystal projector device employs moving the incidence side polarizing plate 58 together with the optical compensating plate 57, the incidence side polarizing plate 58 is caused to incline at the same time when the inclination angle of the optical compensating plate 57 is adjusted after a rotation angle adjustment is made to the incidence side polarizing plate 58. This inclination of the incidence side polarizing plate 58 deteriorates the quality of color images.